The sixth annual Earth Hour kicks off this Saturday, March 31, at 8:30 p.m., triggering a wave of enlightening darkness that will slowly circle the planet. The Australian-led event has exploded into a global tradition since its humble beginnings in 2007, and this year organizers expect the largest turnout in Earth Hour history.

An estimated 5,251 cities and towns in 147 countries will officially participate, turning off various high-profile lights between 8:30 and 9:30 p.m. local time Saturday. This collective show of conservation usually features a who's-who of world landmarks, and this year is no different: The Empire State Building, the St. Louis Gateway Arch, the Eiffel Tower, Christ the Redeemer, Burj Khalifa, the Sydney Opera House and the Great Wall of China are just a few of the major landmarks on the list. Organizers expect to reach 1.8 billion people, or about 25 percent of the entire human population.

Earth Hour's recent growth has largely been due to online chatter, with some 91 million people reportedly connecting on the event's social-media platforms last year. That could be considered ironic, as the AFP reported this week, since every tweet, Tumbl, Stumble and Facebook like uses electricity that is mostly generated with fossil fuels. But it's a cost-benefit analysis, argues Earth Hour executive director Andy Ridley, since the Internet still uses far less energy than many other industrial sectors, including agriculture, manufacturing and transportation.

"Overall, we think that our ability to build a campaign digitally, and to engage with people across the planet in a way that minimizes travel, is one of the great advantages of technology," Ridley tells the AFP, adding that organizers still looked for ways to trim energy use, such as using an intranet social platform and buying carbon offsets.

The idea of sitting in darkness for 60 minutes may sound dull at first, especially to people who are accustomed to 'round-the-clock electrotainment. But it can be surprisingly meditative, offering a rare break from daily routines and encouraging peaceful reflection and introspection. If that still sounds boring, you don't have to just sit at home in the dark — in fact, the decrease in light pollution can make it a great time to go outdoors, whether you try Earth Hour stargazing or simply note which neighbors are negating your noble efforts with fully lit homes.

For more ideas on how to spend Earth Hour 2012, check out this list of suggestions from MNN's Chanie Kirschner. Entertaining children can be a challenge without electricity, but Chanie has several tips (and while it would be a faux pas to do this during Earth Hour itself, you can also entertain your kids before or afterward with one of these official online games).

If you've really got Earth Hour fever this year, consider following organizers' request to "go beyond the hour" and join its I Will If You Will project. The idea is for people, including some celebrities, to dare each other into various environmental pledges. Australian actress Nadya Hutagalung, for example, has pledged to swim with a great white shark if 1,000 people give up plastic bags and straws in 2012.

Check out the official Earth Hour 2012 promo video below — just not between 8:30 and 9:30 on Saturday night.

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